Introduction: Improved access to HIV testing would benefit the one in six Canadians living with undiagnosed HIV, and potentially reduce transmission. Emergency departments may be the first or only point of contact with the healthcare system for people exposed to HIV; however, HIV testing remains inaccessible in many EDs in Canada. Methods: We used a grounded theory approach to characterize the experiences and context of HIV testing in Canadian EDs. We conducted semi-structured phone interviews with ED and public health practitioners from a purposive sample of urban, rural, academic, and community ED catchment areas. Thematic analysis was performed through iterative readings by two authors. Results were triangulated through consultation with public health and HIV experts. Results: Data were obtained from 16 ED physicians and 8 public health practitioners. HIV tests were infrequently performed in the EDs of our sample. Informants from higher incidence regions believed that greater availability of HIV tests in the ED would benefit the populations they serve. In half of the sample, rapid HIV tests were available. However, indications for testing were most often occupational or known high-risk exposure. Notably, two urban EDs in British Columbia screened all patients who otherwise needed blood tests (opt-out), but had shifted to opt-in testing at the time of this study. Consent practices and perceived requirements varied widely between sites; this confused or frustrated physicians. Most EDs were unable to offer a test result to patients during their visit as results were not available until days to weeks later. Commonly, the ordering physician was responsible for communicating results. Some EDs had an assigned physician managing all results on a given day while others relied on public health units for follow-up. All EDs reported access to public health clinics for ongoing care. Barriers to offering a test in the ED included time required for consent, discomfort with pre-test counselling, delay in results availability and unclear processes for follow-up. Conclusion: We describe substantial regional and within-site variation in HIV testing practices across a diverse sample of EDs across Canada. These findings highlight disparities in access to HIV testing and warrant a national discussion on best practices for testing in EDs with an emphasis on reducing barriers for high-risk populations and addressing unmet needs.